The House has passed a "clean" bill to fund the Department of Homeland Security through September, sending the bill to President Obama and averting a partial shutdown of the department. The vote was 257-167.

(CNN) -- U.S. and coalition troops battled supporters of Shiite Muslim cleric Muqtada al-Sadr for a third day Tuesday, with clashes reported in Baghdad and at least four cities in the country's south.

CNN's Wolf Blitzer discussed the uprisings in Iraq with Fawaz Gerges, a professor of international affairs at Sarah Lawrence College in New York.

BLITZER: What exactly did you suspect would happen based on your knowledge of the region?

GERGES: Well, I think the official version in Washington is that most of the attacks were launched by foreign fighters, al Qaeda terrorists and a few small remaining pockets of the former Baathists.

I think what appears to have happened is that the insurgency, the armed insurgency in Iraq, has grown deeper roots in particular within the Sunni Arab community. And now unfortunately it appears to be spreading into many Shiite areas.

And I think what has happened in the last few months is that the insurgency is being led by religious and nationalist sentiment. That is, it's a real insurgency, deeply rooted in nationalist and religious sentiment.

And if this is so, if the thesis is correct that foreign fighters and al Qaeda terrorists and diehard Baathists are playing a marginal role, rather than a substantial one, then, what we are doing now -- military escalation -- will alienate the Iraqi community further and drive many of the members to take arms against the American and coalition forces.

BLITZER: Are you suggesting that there is some sort of alliance of convenience, if you will, between Shiite radicals and Sunni radicals, aligned, united by their hatred of the United States military in Iraq?

GERGES: Let me put it this way. I think the Sunni Arab community has been deeply embittered as a result of the American invasion and toppling of Saddam Hussein. And the community itself has supplied most of the insurgents.

And in particular, many Shiites remained dissatisfied, in particular Muqtada al-Sadr, the fiery young Shiite cleric, who has been a very consistent and steady voice in opposing the American occupation in Iraq.

And this is why I think the worst-case scenario, what we feared the most, was that the insurgency will spread from the so-called Sunni Triangle. The Sunni Triangle is a strategic area of hundreds of square miles in central Iraq, includes Fallujah, Ramadi, Baghdad, the whole Anbar area.

But it seems now, if you look at the Iraqi map, in the last 48 hours or so, the insurgency has spread to almost every single town, Baghdad, Kufa, Basra, Najaf, Nasiriya, Ramadi. This is very serious.

This is what we are witnessing today, a major, major popular uprising.

And to suggest that somehow we have a magical wand by going against Fallujah -- this is what we are doing. We are playing directly into at least the hands of the dissatisfied forces in Iraq.

And at the end of the day, regardless of what you think of the political configuration in the country, there is no military solution to the violent struggle unfolding in Iraq.

We must think of a political exit strategy, a political solution, political solutions to deal with the situation in the country.